How does achievement motivation influence mental effort mobilization? Physiological evidence of deteriorative effects of negative affects on the level of engagement Rémi L. Capa ⁎, Michel Audiffren University of Poitiers, CeRCA, CNRS, France abstract article info Article history: Received 5 May 2009 Received in revised form 24 September 2009 Accepted 24 September 2009 Available online 3 October 2009 Keywords: Mental effort Achievement motivation Approach Avoidance Negative affects Heart rate variability Facial muscle electromyography We tested whether the effect of achievement motivation on effort is modulated by two possible factors of the motivational intensity theory (Wright and Kirby, 2001): perceived difficulty and maximally justified effort. Approach-driven (N = 16) and avoidance-driven (N = 16) participants were first instructed to perform a reaction time task to the best of their abilities. Next, the participants were instructed to consistently beat their performance standard established in the first condition. Approach-driven participants showed a stronger decrease of midfrequency band of heart rate variability, which was used as an index of mental effort, than avoidance-driven participants in the second instruction condition. Moreover, avoidance-driven participants showed a higher corrugator supercilii reactivity, which was used as an index of negative affects, than approach-driven participants in the second instruction condition. No difference of perceived difficulty between groups was observed. Results suggested that avoidance-driven participants developed negative affects in the second instruction condition decreasing the maximally justified effort and their level of engagement. © 2009 Elsevier B.V. All rights reserved. The motivational intensity theory is probably the most productive and relevant theory on cardiovascular reactivity related to mental effort (for reviews see Brehm and Self, 1989; Gendolla and Wright, 2005; Wright and Kirby, 2001). Mental effort is defined as the attentional resources voluntarily allocated by an individual to perform a task (Kahneman, 1973). This theory predicts a linear relationship between mental effort investment and perceived difficulty. The higher the subjective difficulty level, the more effort the individual invests in the task until the individual perceives the level of difficulty as impossible and disengages (Fig. 1A). Mobilization of mental effort is also determined by the maximally justified effort, or the peak of what an individual would be willing to do to succeed. This is also known as the potential motivation (Fig. 1A). A host of research has demonstrated the effects of situational factors affecting the perceived difficulty (e.g. Wright et al., 1997) and the maximally justified effort (e.g. Gendolla and Richter, 2005). Most re- cently, the effects of dispositional factors such as depression (Brinkmann and Gendolla, 2007, 2008), extraversion (Kemper et al., 2008), and achievement motivation (Capa et al., 2008a,b) have been studied. The effects of depression and extraversion on cardiovascular reactivity related to mental effort have been clearly identified and have been proven to be modulated by perceived difficulty. Interpretation of the effect of achievement motivation according to the motivational intensity theory is less clear. The purpose of the study was to clarify whether the effect of achievement motivation on mental effort is modulated by the perceived difficulty or by the maximally justified effort. One previous study demonstrated the interactive effect of achieve- ment motivation and difficulty on mental effort mobilization (Capa et al., 2008a). In this study, approach-driven and avoidance-driven partici- pants had to perform a reaction time task in two different mapping conditions. The first mapping condition was compatible S–R mapping and the second was incompatible S–R mapping. Participants in both conditions were first instructed to “do your best”. Next, they performed the same reaction time task in both mapping conditions, but they received a new set of instructions. The second set of instructions required them to consistently beat their performance standard previously established from the first set of instructions. Approach-driven partici- pants had a higher cardiovascular reactivity related to mental effort than avoidance-driven participants, and especially those during the incom- patible S–R mapping condition. On the other hand, no interactive effect between groups and the different sets of instructions was significant. This point could be explained by the fact that the level of difficulty of instructions was too easy to highlight the effect of achievement motivation on mental effort. However, the manipulation of compatibility and instruction induced a similar increase of subjective difficulty. This implies that the level of difficulty of the instructions was probably sufficient. Another possibility is to consider the lack of reliability of the participants' selection used in this study (Capa et al., 2008a). Approach- driven and avoidance-driven participants were selected on the basis of International Journal of Psychophysiology 74 (2009) 236–242 ⁎ Corresponding author. University of Liège, Department of Cognitive Sciences, 5 Bd. du Rectorat B-32, 4000 Liège, Belgium. Tel.: +32 4 3662008; fax: +32 4 3662859. E-mail address: remi.capa@ulg.ac.be (R.L. Capa). 0167-8760/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpsycho.2009.09.007 Contents lists available at ScienceDirect International Journal of Psychophysiology journal homepage: www.elsevier.com/locate/ijpsycho